Controlling Cabin and Envelope Air Flows and Pressure Differentials to Prevent Envelope Condensation, Enable Cabin Humidification, Improve Fire Safety, and Decrease Fuel Use

Walkinshaw, Douglas S.; Preston, K. F.

doi:10.4271/2011-01-2689

Cited by 5 publications

(4 citation statements)

References 1 publication

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“…Comparing the measured amount of condensate on the frames proves to be in the order of magnitude of the value of 91 g postulated by [11,16]. Measured stack pressure is merely within the estimated 0 to 4.5 Pa of [13].…”

Section: Discussionsupporting

confidence: 63%

“…First, the typical cabin cruise pressure is 750 hPa whereas the lab ambient air pressure is approximately 940 hPa (the lab is at 694 m elevation). In a comparison performed by [13], pressure differences are estimated approximately 20% lower in cruise than in ground pressure conditions. On the other hand, typical cruise exterior conditions are −56.5 • C [2], whereas the LITE chamber achieves around −30 • C. Furthermore, the chamber considers a rather undisturbed section of the fuselage, without the presence of, e.g., doors or riser ducts.…”

Section: Discussionmentioning

confidence: 95%

“…Due to the temperature difference between the warm cabin and crown section and the cold exterior skin, a stack pressure forms [13,14], resulting in a pressure difference and consequently an airflow towards the skin cavity in the upper section of the aircraft envelope. Reference [13] estimates the magnitude of the driving stack pressure to around 4 Pa and shows the correlation between of the sizes of leakages in the insulation layer and the resulting air ingress. Reference [15] developed a simplified test setup representing a field section of the cabin sidewall and investigated the frost buildup with and without insulation blanket installed.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of the Impact of a Particle Foam Insulation on Airflow, Temperature Distribution, Pressure Profile and Frost Buildup on the Aircraft Structure

Norrefeldt

Riedl

2021

Aerospace

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Aircraft insulation separates the thermally comfortable cabin interior environment from the extremely cold outside conditions. However, the fabrication and installation of the insulation in the aircraft is a labor-intensive task. Tailored, rigid particle foam parts could be a solution to speed up the installation process. The presented study investigates the feasibility of such a concept from a hygrothermal point of view. Due to the temperature difference between the cold air trapped between aircraft skin and insulation on one side and the warm cabin air on the other side, a buoyancy-induced pressure difference forms. This effect drives the warmer air through leakages in the insulation system towards the cold skin. Here, moisture contained in the air condenses on the cold surfaces, increasing the risk for uncontrolled dripping (“rain in the plane”) when it melts. Therefore, this study compares the condensate build-up of different installations of a rigid particle foam frame insulation with the classical glass fiber capstrip. Tests are hosted in the Fraunhofer Lining and Insulation Test Environment chamber. It is shown that careful installation of the particle foam frame insulation provides similar level of moisture protection as the current state of the art insulation, and that the condensate amount does not depend on the amount of airflow directly behind the sidewall.

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Section: Discussionsupporting

confidence: 63%

Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Investigation of the Impact of a Particle Foam Insulation on Airflow, Temperature Distribution, Pressure Profile and Frost Buildup on the Aircraft Structure

Norrefeldt

Riedl

2021

Aerospace

View full text Add to dashboard Cite

show abstract

“…[5] reviews data from a survey conducted by [2] on the B757 fleet and concludes an average daily amount of 91g of water condensation per field. [3] estimates the magnitude of the driving stack pressure to 4 Pa and shows the correlation between the sizes of leakages in the insulation layer and the resulting air ingress. Thus, a careful installation of the insulation blankets helps reducing moisture related issues.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the impact of a particle foam insulation on frost buildup on the aircraft structure

Norrefeldt

Riedl

2022

IOP Conf. Ser.: Mater. Sci. Eng.

View full text Add to dashboard Cite

The aircraft insulation separates the thermally comfortable cabin interior environment from the extremely cold outside condition. However, the fabrication and installation of the insulation in the aircraft is a labour intensive task. Tailored, rigid particle foam parts could be a solution to speed up installation process. The presented study investigates the feasibility of such a concept from a hygrothermal point of view. Due to the temperature difference between the cold air trapped between aircraft skin and insulation on one side and the warm cabin air on the other side, a buoyancy induced pressure difference forms. This effect drives the warmer air through leakages in the insulation system towards the cold skin. Here, moisture contained in the air condenses on the cold surfaces, increasing the risk for uncontrolled dripping (“rain in the plane”) when it melts. Therefore, this study compares the frost build-up of different installations of a rigid particle foam frame insulation with the classical glass fiber capstrip. Tests are hosted in the Fraunhofer Lining and Insulation Test Environment chamber.

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Modeling and Measuring the Leaked-Air Rate into the Insulation Layer of a Single-Aisle Aircraft Cabin

2022

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Leaked air from an aircraft cabin into its envelope walls through cracks can lead to a large amount of moisture condensation on inner shell skins and in insulation layers. The leaked-air rate is subject to the stack pressure difference and the geometry of the cracks. So far, the impacts of the crack sizes and positions, and the flight conditions on the resulting leaked-air rate have been unclear. This investigation adopts validated computational fluid dynamics (CFD) to model leaked flow, pressure, and temperature distribution in a single-aisle aircraft cabin. Impacts of the flight cruising altitude, crack size and position, and flow blocker on the leaked-air rate were examined. In addition, measurements were conducted in a reduced-scale cabin mockup in an environmental chamber to mimic flight conditions. Obtained test data were adopted to validate CFD modeling. Results reveal that a higher cruising altitude of a flight results in greater leaked-air rate from the cabin to the envelope walls due to the larger temperature difference. The smaller the crack size was, the lower the leaked-air rate. In addition, more cracks farther away from the neutral plane lead to a greater leaked-air rate. A flow blocker in the middle of the insulation layer reduced the leaked-air rate by 34.5%.

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Controlling Cabin and Envelope Air Flows and Pressure Differentials to Prevent Envelope Condensation, Enable Cabin Humidification, Improve Fire Safety, and Decrease Fuel Use

Cited by 5 publications

References 1 publication

Investigation of the Impact of a Particle Foam Insulation on Airflow, Temperature Distribution, Pressure Profile and Frost Buildup on the Aircraft Structure

Investigation of the Impact of a Particle Foam Insulation on Airflow, Temperature Distribution, Pressure Profile and Frost Buildup on the Aircraft Structure

Investigation of the impact of a particle foam insulation on frost buildup on the aircraft structure

Modeling and Measuring the Leaked-Air Rate into the Insulation Layer of a Single-Aisle Aircraft Cabin

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